The present invention relates to a fuel injection valve including injection holes having different diameters, an internal combustion engine including the fuel injection valve and a fuel injection method using the fuel injection valve.
A fuel injection valve used for a typical gasoline engine has a plurality of injection holes. The plurality of injection holes formed in one fuel injection valve have the same diameter. Penetrations of fuel sprays against the air flow in a cylinder depend on the momentum of the fuel sprays from the individual injection holes, and, since the fuel sprays from the same type of injection holes have the same momentum, the penetrations of the individual fuel sprays are the same. Note that a penetration refers to a fuel spray travel distance, however, does not necessarily refers to a final fuel spray travel distance, but often refers to a fuel spray travel distance at a certain point of time. Mentioning the relation between penetration and penetration force, a penetration is a fuel spray travel distance, and the travel distance is determined from the penetration force (or initial spray momentum) decelerated by a surrounding fluid, so there is a strong correlation between the penetration force and the penetration.
In contrast, JP-A-2004-232583 discloses a fuel injection valve in an internal combustion engine that injects fuel into a cavity unsymmetrically. As shown in FIG. 3 in the disclosure, the multi-hole injection valve includes a plurality of injection holes having different diameters in which a larger number of injection holes having a larger diameter are directed toward the intake side, while a smaller number of injection holes having a smaller diameter are directed toward the exhaust side. Furthermore, this fuel injection valve is in a center-mount configuration, i.e., is positioned in the center of a cylinder head.
Furthermore, in an internal combustion engine according to JP-A-2004-232583, fuel is injected unsymmetrically between the intake side and the exhaust side in the cylinder according to tumble flow that is unsymmetrical between the intake side and the exhaust side in an attempt to generate a more homogeneous fuel-air mixture by the action of tumble flow (see paragraph [0019]).